1. Field of the Invention
The present invention relates generally to electrical adapters for mobile phones, portable notebook computers and associated chargers, and more particularly to electrical adapters having both a retractable cable assembly that is used to store corresponding cables in a convenient manner, and an electrical plug assembly for use with various types of electrical outlets.
2. Description of the Prior Art
A wide variety of electrical devices typically draw AC power from a commercial source, usually delivered through a wall receptacle or socket, but require that this AC power be converted into one or more DC voltages for powering these devices. Electrical adapters have been used extensively throughout the world to provide such DC voltages to these electrical devices.
FIG. 1 is a perspective view of an exemplary prior art electrical adapter having a long cable. Typically, when a consumer first purchases electrical adapter 10 from the manufacturer, it arrives with the electrical cable 12 bundled and tied with a wire-twist 16 as shown. Cable 12 is coupled to a plug 14 for connection with the electrical device (not shown). Removing the wire-twist allows the cable to be used in an extended fashion over its entire length. As is seen, cable 12 is a low voltage cable for carrying the DC voltage to the mobile electrical device, which may be a portable personal computer (e.g. notebook), mobile phone, or a corresponding electrical charger that requires operation from an AC power source. Although not shown in FIG. 1, electrical adapter 10 includes a converter for converting the AC power to a DC output voltage.
As shown in the perspective view of FIG. 2, electrical adapter 10 is further coupled to a high voltage cable 16, for conventionally carrying the AC power from a conventional AC power outlet, via a receptacle plug 18 shaped to enable for insertion into the AC power socket. Similarly with respect to cable 12, a user upon purchasing the electrical adapter typically finds cable 16 tied with a wire-twist from the manufacturer. With use however, these cables 12, 16 become tangled and twisted, thereby making the electrical adapter 10 logistically awkward as a unit to use, as seen in FIG. 2. This is especially true when the electrical adapter is used for providing power to a portable personal computer having a variety of attachments each requiring a separate cable attached to the port of the computer and to the peripheral devices. The multiple cables generally become tangled and interfere with use of the electrical device. For example, a portable computer powered using the electrical adapter situated at a desk with many other peripheral devices attached thereto in close proximity to a wall-mounted electrical receptacle may have many wires in a tangled state.
Additionally, a problem with the conventional electrical adapter 10 is that the cables 12, 16 are often wound around the unit by hand and stored loosely as shown in FIG. 2. This is highly undesirable since it may result in the cables unraveling and the unit becoming bulky, thereby being especially cumbersome when the electrical adapter is put into a briefcase. Excessive wear and tear of the cables may also be experienced as a result. Depending upon the patience of the consumer, the cables may be tied together to prevent unraveling, usually with a wire-twist, rubber band, tie-wrap or string.
Consequently, what is desired is a means for storing the cables of an electrical adapter efficiently and conveniently, including means that would be feasible especially in situations where the adapter is used while or in situations where portability of the electrical device being powered by the adapter is essential. What is needed is a suitably small ergonomic means for retracting the cables, thereby allowing the cables to be selectively stored when not required by the user. It would be ideal if the cables could be stored and retrieved, as a user desires. This would allow a consumer to selectively extend or shorten the cabling of the electrical adapter on an as-needed basis depending upon the circumstances and application.
Retractable cable assemblies are one solution to the problem of selectively extending and shortening the cabling ergonomically. For example, retractable cable assemblies are commonly used for the AC cord on a vacuum cleaner. However, in such applications, there are few size constraints on the retraction mechanism. Additionally, retractable cables are often used for the cable connecting earphones to a personal stereo. These conventional retractable cable assemblies, while providing convenient cable handling, are inadequate for addressing the challenges faced with those electrical devices in the nature of a notebook computer or mobile phone. The challenge that the inventors of the present invention face concern electrical adapters for electrical devices that include cables carrying significantly more current (e.g., 2-5 Amps) than a cable for an earphone and require a heavier gauge wire which is less flexible and therefore difficult to retract. Because size is critical for the electrical adapter of the present invention, the conventional retractable mechanisms for storage of cables of vacuum cleaners and stereo earphones are ill-suited. What is therefore needed is a retractable cable assembly that is part of an electrical adapter that provides a compact manner for storing a low voltage cable, which may require heavy copper in the wire for a given adapter power rating.
The retractable cable assemblies of the prior art often comprises a retractor having a base subassembly supporting a reel. The reel is known by several names, including a spool or wheel. FIG. 3 shows a partially-exploded perspective view of a retractor 30 of the prior art having a base subassembly 32 rotatably supporting reel 34 thereabout. Reel 34 is operable to rotatably wind and unwind a cable 36 by means of a torsion spring coil 38 that is biased in a predetermined direction. Although not shown, the retractor 30 is commonly controlled to selectively preclude rotation of the reel 34 relative to the subassembly 32 by frictionally engaging and locking the reel. A drawback with such conventional retractors is that they include circular electrical contacts 39 disposed along the center portion of the cable reel 34. This results in a larger area being required to implement the electrical contact between the cable and circuitry of the electrical adapter. Another problem with this embodiment is that it results in greater friction being exerted on the cables and their electrical contact points. This is highly undesirable since it may result in accelerated wear-and-tear of the connections and components, thereby leading to earlier degradation of the retractor. Such degradation leads to the integrity of the electrical contacts being compromised. Moreover, the structure of the circular contacts 39 in the conventional retractor, such as that shown in FIG. 3, substantially increases the cost and complexity of manufacturing. Consequently, what is desired is an improved retractor that provides the benefits of minimizing the size of the electromechanical components, of reducing the friction between the cable and the electrical contacts occurring during rotation of the reel, and of providing a cost-effective manner of fabrication.
Because many electrical devices are sold for use throughout the world, and because a world standard for electrical power requirements is lacking for the operation of these electrical devices, it would be highly desirable to provide an electrical adapter that is not only portable, but is able to accommodate various electrical plug assemblies, which may include a high voltage plug and converter circuitry, used in different parts of the world. Where the electrical devices are notebook computers and mobile phones used with electrical adapters that have electrical plugs inserted into an electrical receptacle, it would be beneficial if the electrical adapter is suitable for use with several country""s electrical plug requirements. With people traveling worldwide, it is unpredictable for the consumer to know which particular type of receptacle will be employed in a destination country. To carry several adapters and adapter prongs while traveling and to anticipate a particular country""s electrical prong being used is not only logistically cumbersome, but also a burden, as multiple parts become easily lost. Conventionally, the converters within the electrical adapters are designed to receive a range of voltage inputs so that only a single adapter need be carried. But, in order to comply with various outlets that deliver AC power around the world, consumers typically carry a variety of input cords, each with a different type of plug. Moreover, there are commercially available electrical adapters sold for the purpose of accommodating travelers, and which are mechanical assemblies having on one end an electric plug, and on the other end, a socket accepting the standard plug interengageable with a particular country""s type of receptacle. However, the parts required for these options are very bulky and can be heavy. Although these conventional electrical adapters permit the conversion of one type of electrical energy to another type, and fulfill their respective, particular objectives and requirements, they do not disclose an adapter with a retractable cable assembly and interchangeable electrical plug assembly for use with a mobile phone, portable personal computer and their corresponding chargers that overcome all of the above-mentioned drawbacks.
Consequently, it would be advantageous if a consumer could use a single electrical adapter with the storage functions desired herein, in an interchangeable manner so as to accommodate various types of electrical receptacles, and with a size of the conventional AC/DC adapter package being considerably reduced by restructuring the cable storage and packaging criteria.
The present invention is directed towards an electrical adapter having a retractable cable assembly for a low voltage cable, where the electrical contacts of the retractable cable assembly are disposed along an axis of rotation to minimize the friction between the cable and contacts therein when the cable is selectively extended and retracted. The electrical contacts of the present invention enable constant electrical conduction between components when the cable is extended from and retracted into the retractable cable assembly.
In a preferred embodiment, the retractable cable assembly of the present invention is supported by a housing and generally comprises a cable coupled at one end to an electrical plug for outputting or receiving a first voltage; and means for retracting the cable which is supported by said housing. The means for retracting the cable includes a base subassembly having support means extending along a central axis and first means for defining a bore disposed along the central axis and within the support means. The retractable cable assembly further includes a first contact means defining a shaft and having a first terminal offset laterally of the shaft, where the first terminal is disposed in generally parallel relationship to the shaft. The first contact means is supported by the base subassembly when the shaft is inserted through the bore and extends therethrough, and the first terminal is in electrical contact with the shaft. The retractable cable assembly further includes second contact means defining a sleeve and having a second terminal offset laterally of the sleeve, where the second terminal is disposed in generally parallel relationship to the sleeve, and the second contact means is supported by the base subassembly when the support means is inserted through the sleeve and extends therethrough, the second terminal being in electrical contact with said sleeve, wherein said cable is supported by the means for retracting the cable. The retractable cable assembly also includes a pair of terminals disposed external to the housing and coupled respectively to the first and second contact means to enable the first voltage to be provided to or received from the assembly.
One important technical aspect of the preferred embodiment of the retractable cable assembly is that the means for retracting the cable includes a reel having means defining a bore therein so that the support means may be inserted therethrough to enable the reel to be rotatably operable about the central axis for dispensing and retracting the cable. The reel includes first and second slot means disposed adjacent the means for defining a bore. The means for retracting the cable further includes: a first interengageable contact supported by the first slot means and being in electrical contact with and rotating about the shaft; and a second interengageable contact supported by the second slot means and being in electrical contact with and rotating about the sleeve, wherein the cable comprises a plurality of conductors each coupled to a respective one of the first and second interengageable contacts.
Another important technical aspect of the preferred embodiment of the retractable cable assembly pertains to the contacts defining a sleeve, which includes a spiral portion for maintaining continuous electrical contact with the second interengageable contact as the second interengageable contact rotates about the sleeve. The second interengageable contact includes a pair of edges defining a gap therein, and the sleeve includes a spiraled inclined portion so as to avoid the problem of intermittent electrical contact that could arise with the gap rotating about the sleeve and coinciding with gaps within the sleeve.
One object of the preferred embodiment of the present invention is to provide a low cost retractable cable assembly with first and second interchangeable contacts readily interengageable with the first contact means and the second contact means, respectively.
Another object of the present invention is the reduction in both the size of the electrical adapter and the frictional forces caused by cable extension and retraction by providing electrical contacts in the retractable cable assembly disposed adjacent to a central shaft residing along the center axis of rotation for the retractable cable assembly. The present invention thereby overcomes the deficiencies of conventional retraction mechanisms.
According to the invention, the retractable cable assembly may be utilized in a number of ways. In a first embodiment, the retractable cable assembly is used on the DC side of an electrical adapter. In this embodiment, the electrical adapter includes a housing; an electrical plug assembly supported by the housing, wherein the electrical plug assembly includes an interchangeable module coupled to an adapter module, the interchangeable module having a plurality of prongs for receiving a first voltage when mated with an electrical receptacle; a converter electrically coupled to the assembly for converting the first voltage to a second voltage; and a retractable cable assembly supported by the housing and electrically coupled to the converter. The retractable cable assembly includes: a cable coupled at one end to the converter for receiving the second voltage and coupled at another end to an electrical plug for outputting the second voltage; a reel for winding and unwinding the cable, the reel being rotatably supported by the housing; a pair of first contacts, one of which is supported by the reel and rotatable about the other of the first contacts; and a pair of second contacts, one of which is supported by the reel and rotatable about the other of the second contacts.
Yet another object of the present invention is to enable the electrical adapter to be used in a variety of countries, each having a different receptacle plug configuration by including the interchangeable module coupled to an adapter module. The interchangeable module comprises a plurality of prongs and an opening for receiving a mating portion extending from the adapter module.
In a second embodiment, the retractable cable assembly is used on the DC side of an electrical adapter having: a housing; an electrical plug assembly supported by the housing, wherein the electrical plug assembly includes an AC cord coupled to a receptacle plug for receiving a first voltage when mated with an electrical receptacle; a converter electrically coupled to the assembly for converting the first voltage to a second voltage; and a retractable cable assembly supported by the housing and electrically coupled to the converter.
In a third embodiment of the present invention, the retractable cable assembly is used on the AC side of an electrical adapter having: a housing; an electrical plug assembly supported by the housing and including a regulator coupled to a first electrical plug for pre-regulating a first voltage to an intermediate voltage, the first voltage being received when the first electrical plug is mated with a receptacle, the first electrical plug having a plurality of prongs, and a retractable cable assembly; a converter for converting the intermediate voltage to a second voltage; and a second cable coupled at one end to the converter for receiving the second voltage and coupled at another end to a second electrical plug for outputting the second voltage. The retractable cable assembly includes: a reel for winding and unwinding a first cable, the reel being rotatably supported by the housing; a pair of first contacts, one of which is supported by the reel and rotatable about the other of the first contacts; and a pair of second contacts, one of which is supported by the reel and rotatable about the other of the second contacts, wherein the cable is coupled at one end to the regulator for receiving the second voltage and at another end to corresponding ones of the first and second contacts.
Still another object of the present invention is to provide an electrical adapter having a retractable cable assembly for storing cables carrying not only the low voltages, but also higher voltages. By including a voltage step-down circuit in the AC plug, the higher AC voltage may be converted to a lower isolated (intermediate) DC voltage, which is then used as an input to the converter. This arrangement allows the intermediate voltage to be optimized so as to permit a flexible cable to be used with a retractable cable assembly of the present invention. With this inventive arrangement, higher power levels may be used with the retractable cable assembly of the present invention.
In a fourth embodiment of the present invention, the retractable cable assembly is used on the AC side of an electrical adapter having: a housing; an electrical plug assembly supported by the housing and including a regulator coupled to a first electrical plug for pre-regulating a first voltage to an intermediate voltage, the first voltage being received when the first electrical plug is mated with a receptacle, the first electrical plug having a plurality of prongs, and a retractable cable assembly; a converter for converting the intermediate voltage to a second voltage; and a modem having modem cable coupled at one end to the converter for receiving the second voltage and coupled at another end to a second electrical plug for outputting the second voltage. The retractable cable assembly includes a similar structure to that described in the third embodiment.
In a fifth embodiment of the present invention, an electrical plug device includes an electrical plug having a plurality of prongs for receiving a first voltage when mated with an electrical receptacle; a voltage step-down circuit coupled to the electrical plug for converting the first voltage into a second voltage; and a cable having one end coupled to the circuit and another end coupled to a retractable cable assembly, wherein the cable is used for transferring the second voltage to the retractable cable assembly.
Still another object of the present invention is a low cost manufacturing method to fabricate a retractable cable assembly for use in an electrical adapter.
These and other objects of the present invention will become apparent to those skilled in the art from the following detailed description of the invention and embodiments, the accompanying drawings, specification, and claims.